Bleaching of textiles with chlorine monoxide

ABSTRACT

A process is provided for the bleaching of a raw natural fiber, either alone or in combination with a synthetic fiber, either in open-width or in rope form. The process comprises contacting the textile material at a suitable moisture content (e.g. in the range of about 80 to about 20% by weight), with chlorine monoxide which is in admixture with an inert gaseous or liquid solvent, the chlorine monoxide being present in an amount of about 0.1 to about 1.0% on the weight of the dry fabric. If the chlorine monoxide is in gaseous form, it is generally at a partial pressure of about 1 to about 253 Torr, and the contact time is less than about 1 second up to about 300 seconds. The terminal pH is selectively adjusted to about 1 to about 13.

li'lUCiel United States Patent Liebergott et al.

14 1 Sept. 30, 1975 1 BLEACI-IING OF TEXTILES WITI-I CHLORINE MONOXIDE 211 Appl. No.: 360,974

[30] Foreign Application Priority Data May 30, 1972 Canada 143425 [52] US. Cl. 8/108; 8/115.7; 162/66 [51] Int. Cl.- D06L 3/06 [58] Field of Search 8/108, 115.7; 162/66 [56] References Cited UNITED STATES PATENTS 3,291,559 12/1966 .Robson 8/108 3.560.330 2/1971 Ahlborg.... 8/108 3,579,419 5/1971 Yorston 8/108 3.585.147 6/1971 Gordon 8/108 3,619.349 11/1971 Liebergott 8/108 3.655.505 4/1972 Yorston 8/108 FOREIGN PATENTS OR APPLICATIONS 34.704 2/1886 Germany Roymoulik 8/108 Croon 21/108 Primary E.\'aminerBenjamin R. Padgett Assistant E.\'aminerDonald P. Walsh Attorney, Agent, or FirmMillen, Raptes & White [57] ABSTRACT A process is provided for the bleaching of a raw natural fiber, either alone or in combination with a syn' thetic fiber, either in open-width or in rope form. The process comprises contacting the textile material at a suitable moisture content (eg. in the range of about 80 to about 20% by weight), with chlorine monoxide which is in admixture with an inert gaseous or liquid solvent. the chlorine monoxide being present in an amount of about 0.1 to about 1.0% on the weight of the dry fabric. If the chlorine monoxide is in gaseous form, it is generally at a partial pressure of about 1 to about 253 Torr, and the contact time is less than about 1 second up to about 300 seconds. The terminal pH is selectively adjusted to about 1 to about 13.

23 Claims, No Drawings BLEACHING OF TEXTILES WITH CHLORINE MONOXIDE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the bleaching of textiles. More particularly, it relates to the bleaching of raw, natural fibers and synthetic fibers, either alone or together, in open-width or in rope form.

As used herein, and in the textile industry generally, the term bleaching" includes bleaching per se as well as other related operations designed to purify fibers and fabrics by removing natural and processing soils and colours. The bleaching process may de-size, caustic'scour, and acid sour goods, in addition actually to bleaching them. The condition of the fibers, their sensitivity to bleaching chemicals and to mechanical handling, and the intended use of the goods all contribute to determine the type of bleaching process selected.

2. Description of the Prior Art The prior art teaches that cotton and man-made synthetic fibers are bleached by a multitude of bleaching chemicals which include: sodium and calcium hypochlorite, sodium chlorite (sodium acetate and glacial acetic acid buffers), peracetic acid, and alkaline peroxide solutions containing sodium silicate, sodium hydroxide and magnesium sulphate. [See, for example, (1 The Bleaching of Textiles, in The Encyclopedia of Polymer Science and Technology, pages 438 to 466, Vol.2, 1965, and (2) Review Textile Bleaching in the United States, published by Ciba-Geigy Limited,

Sometimes cotton is bleached immediately after opening; more often it is bleached after the spinning operation. Spun yarn for weaving can be bleached in hank form on the beams or rods of a skeleton cylinder. Wool and knitted goods are frequently bleached before dyeing or printing.

Natural raw-fiber stock, yarn, knitgoods, and woven piece goods are bleached for white finishing, printing, and dye bottoms. Although most synthetic fibers require bleaching only for special uses, blends of natural and synthetic fibers are often bleached to whiten the natural fibers. Occasionally, bleaching may be necessary to redress the colour of a synthetic fiber which has yellowed during heatsetting. With blends, the bleaching process selected is that least damaging to the most sensitive fiber in the blend. Chlorine bleaches and strongly alkaline solutions damage wool and other protein fibers, notably silk.

Raw wool requires a washing-scouring-acid bleaching (or alkaline peroxide) bleaching operation to remove the natural water-soluble, saponifiable, and oxidizable impurities. Wool yarns, knits, and woven fabrics are commonly bleached by steeping in hydrogen peroxide solutions at a maximum pH of about 9.6 and a temperature of about 1 16 to about 120F.

Cotton is comparatively resistant to bleaching chemicals and temperatures, but control of bath conditions is necessary for optimum bleaching with minimum fiber degradation For example, neutral chlorine bleaches damage cotton; chlorine bleaches are therefore used at alkaline pH.

The man-made cellulosic fibers are more sensitive to alkalies and high temperatures than is cotton; cellulose acetate is more sensitive than rayon. Most acrylic fibers and fabricsare scoured in mildly alkaline detergent solutions containing perborates and silicates.

Acrylic-cotton blends can be bleached batchwise or continuously in hydrogen peroxide-sodium silicate formulations having a pH of about 9.0 to about 10.0. Acrylic-wool blends can be bleached using the standard wool-bleaching techniques. Nylon and nylon blends containing over about 50% nylon are usually bleached with sodium chlorite or with peracetic acid. Nylon-cotton blends can be bleached with hypochlorite or peroxide bleaches. Most polyester fibers are white as produced, but require a scour to remove the processing oils and waxes. Polyestercotton-nylon blends are scoured similarly to cotton. Polyester fabrics and polyester blends may be bleached using chlorite bleaches or peroxide bleaches.

Since high alkalinity, high temperatures, and high peroxide concentrations may injure certain synthetic fibers, acid sodium chlorite bleaches are often recommended for synthetics and synthetic-cotton blends. As with hypochlorite bleaches, an antichlor should follow the sodium chlorite bleach to ensure against yellowing of the bleached fibers upon subsequent exposure to high temperatures, such as those commonly used in drycleaning and pressing. Inasmuch as acid sodium chlorite is not an effective cotton bleach unless preceded by a caustic scour, mildly alkaline peroxide solutions are often used to bleach syntheticcotton blends. Here, the absorbency of the cotton (which consumes the chemicals) prevents degradation of the synthetic fibers by the solutions. High temperatures in combination with high peroxide concentrations and high pH values may severely degrade nylon. Alkaline peroxide solutions yellow acrylic fibers at pH values above about 10; temperatures above about F. may cause per manent yellowing. Strong alkalies hydrolyze poly(ethylene terephthalates) to water-soluble products; however, at normal concentrations, cotton-bleaching agents do not adversely affect most polyester fibers. Peracetic acid (at a concentration of about 40%) finds some use in bleaching nylon and other synthetics for specialty products, such as knit goods. Whiteners give adequate results for most goods.

Since peroxide bleaching is applicable to all natural fibers, it is particularly suited to the processing of fabric blends. Peroxide bleaches are chemically less reactive than hypochlorite bleaches and therefore cause less fiber degradation and less injury to dyed yarns. As a result, peroxide bleaching gives permanently white bleached goods with good absorbency and excellent appearance, hand, loft, and elasticity.

Alkaline peroxide solutions tend to yellow some synthetic fibers, particularly acrylic fibers. Peracetic acid and sodium chlorite bleaches, which have found some use in commercial bleaching in the past decade, have little degrading action on most synthetics and have good bleaching action on their blends with cellulosic fibers. A preliminary wash, wetting-out", or scour normally precedes the actual bleaching operation as an integral part of the overall process of fabric preparation.

As noted above, then, the formulations, temperatures, and treating periods used in scouring and bleaching textiles depend on the material treated and on the machinery used. In the processing of blended fabrics, the conditions must meet the requirementsof the most sensitive component of the blend. Accordingly, it

would be advantageous to provide a bleaching agent and process for bleaching of textiles which would be useful for bleaching the variety of textile materials noted above.

There are four fundamental steps in the de-sizing, scouring, and bleaching operations in conventional procedures used to prepare cloth, namely: l) saturating the goods (the textile material to be treated) with the chemical solution; (2) heating the saturated goods to an optimum temperature; (3) storing the hot, saturated goods to permit the chemicals to react; and (4) washing the goods to remove unreacted chemicals and reaction by-products. These steps may be carried out in a batch system or in a continuous system.

In batch systems these steps are carried out in vats,

kiers, dolly washers, or other machines equipped to' move the goods through the chemicals solutions or to circulate the solutions through the goods.

Continuous bleaching systems have drive mechanisms coupled with suitably designed units for each step to permit quasi-automation of the consecutive steps. A continuous scouring and peroxide-bleaching system generally uses stainless-steel equipment 'designed to process fabric in either rope or in open-width form. Standard washers are used in a continuous line, tight-strand washers for high-speed rope operation or slack washers for low-speed operation. Saturators for rope processing are actually single-strand washers equipped with a small entrance chute at one end and a set of squeeze rolls at the other. For open-width processing, a multiple-bowl or open-type washer is satisfactory. It generally consists of a series of washers, chemical saturators, and J-boxes or other storage devices, operated in line and so synchronized that a uniform production results. The J-box, the preferred storageconveyor device, provides for holding the goods hot, either after preheating or by steaming during stor age. Since heating accelerates peroxide decomposition, direct heating of a peroxide saturator solution is uneconomical in a continuous system. Therefore the cloth is first saturated, then heated and stored in a J-box or similar device long enough to permit effective bleaching. The washing step between the caustic and the bleaching steps must be thorough for good-quality work at moderate costs.

Thus, most continuous processes conventionally used are provided with one .I-box for the caustic soda scour and a second J-box for the hydrogen peroxide bleach. Each J-box provides for about one hour retention time and heats the saturated cloth to a temperature of from about 205F. to about 212F. The conventional sequence for cotton cloth in rope form is: singe; quench with an enzyme solution; lay in bins at least four hours; rinse; saturate with caustic soda; steam in a .I-box for about 1 to about 1 /2 hours; rinse; saturated with hydrogen peroxide bleach solution; steam in J-box one hour; rinse; and finally pile in white bins.

Such equipment, and the processes using them, suffer many disadvantages. The conveyor type steams are space consuming, expensive, and prone to mechanical difficulties. The open-width J-box ranges in use do not prevent permanent fold marks and creases in sensitive fabrics. in fact, these .l-boxes frequently inflect abrasion marks, so that the quality of the cloth bleached in them is generally poor. Moreover, rinsing in openwidth machines is not-adequate for continuous processing. Furthermore, even such continuous processes are very lengthy, eg of the order of about 6 to about 7 hours.

Other continuous processes have been developed in an effort to speed up the process by the use of pressures up to three atmospheres. Such continuous pressure equipment (of the Kleinewefer and Mather-Flatt designs) are designed to scour or bleach in as little as about 40 seconds, but generally the time ranges from about 60 to about seconds. The cloth is adapted to move within a speed range of about 75 to about yards per minute with the pressure being maintained at about 30 psig, about 43 psig, or up to about 60 psig. However, such machines and processes have certain inherent features which generally prevent satisfactory processing of more than two or three fabric constructions.

Another system is the so-called continuous kier system in which the dry cloth enters the saturator and then passes into a J-box where it is steamed as it moves down the straight section of the J. Diluted bleach solution enters the J-box at the top of the curve, circulates through the cloth, and leaves near the exit end of the .l-box. This circulation through the cloth is similar to the flow of solution in a kier. This system, although relatively rapid, suffers the general deficiencies of the use of the J-box as a conveyor-storage device.

Accordingly, it would be advantageous to provide a process which would make use of existing apparatus in cluding the J-box and continuous kier and high pressure types, to bleach the wide variety of textile fibers hereinabove described, with a single and universally acceptable bleaching agent. Such process should, ideally, use the J-box almost exclusively as a conveyor device, and should preferably minimize or obviate a saturating step.

The greatest deficiency of the prior art, as above noted, is that when cotton, a raw, natural fiber, is in combination with a synthetic fiber, e. g. as blends of cotton, with polyester, rayon, acetate and acrylic fibers, in open-width or rope form, a different reagent must be used in order to utilize a specific pH range for such various fabric compositions. Also, the fabric, in all cases, whether a batch type process or any of the continuous type processes above described is used, must be immersed into the aqueous bleaching solution to saturate it.

Many patents have proposed the continuous processing of fibers, threads and fabrics of such textile materials as cotton, linen, jute, hemp, regenerated cellulose, nylon, etc. with hypochlorite (US. Pat. Nos. 2,302,936 and 2,602,723); alkali metal chlorites (U.S. Pat. Nos. 3,120,424 and 3,521,991); and with chlorine dioxide and a peroxidized component (U.S. Pat. No. 3,619,1 10). However, these patents are not directed to processes which are universally effective with many different fibers.

SUMMARY OF THE INVENTION Aims of the Invention An object of a broad aspect of this invention is to provide an improved simple process for the bleaching of a raw, natural fiber, such as, for example, cotton, linen, jute, hemp, etc., alone or in combination with a synthetic fiber such as, for example, polyamides, (e.g. the nylons, for example Nylon 66, Nylon 6, Nylon 4, Nylon 610 [Trademarked Tynex], Nylon 11 [Trademarked Rilsan], Nylon 12, and Nylon 9), polyesters isoprene and their copolymers), etc., in open-width or in rope form, so that one reagent could be employed (e.g. polyethylene terephthalate [trademarked Terylene and Dacron]), rayon, modified rayon, acetates (e.g. cellulose acetate [trademarked Acele] and cellulose triacetate [trade marked Arnel]), acrylic fibers (e.g. a long chain synthetic polymer composed of at least 85% by weight acrylonitrile units, for example, the synthetic acrylicfibers known by the trade marks of Acrilan, Creslan, Orlon and Zefran), and polyolefins (e.g. polyethylene, polypropylene, polybutenes, polyfor all blends of fabric.

An object of another aspect of this invention is to provide an improved textile bleaching process using some of the existing equipment, such as the .I-box, to conduct the treatment of bleaching with a gaseous bleaching agent under atmospheric conditions, or at a partial pressure of from about 1 to about 253 Torr.

An object of yet another aspect of this invention is the provision of a textile bleaching process which is operable in the acid, neutral or alkaline range, thereby substantially eliminating the need for changing chemicals for different combinations of natural and synthetic fibers, and consequently simplifying the bleaching of 2 textiles.

An object of yet another aspect of this invention is the provision of such a process in which the saturating step with the bleaching agent may be obviated.

I Statement of Invention 3 Applicants have found that, in the bleaching of a raw, natural fiber, alone or in combination with a synthetic fiber, in open-width or rope form, chlorine monoxide can be used with advantage where other chemicals were heretofore being used. In particular, the applicants have found that by using chlorine monoxide to achieve a bleaching effect on the fabric, the period of contact between chlorine monoxide and the raw, natural fiber, alone, or in combination with a synthetic fiber, in open-width or rope form, can be within the range of from a fraction of a second up to about 300 seconds. This rapid bleaching affords better control over the bleaching operation, and a further saving in bleaching chemicals.

By a broad aspect of this invention, then, there is provided in a process for the bleaching of a raw, natural Other Features of the Invention By another aspect of this invention, a process is provided for the bleaching of a raw, natural fiber, alone or in combination with a synthetic fiber, in open-width or rope form, which comprises contacting the material, at a suitable moisture content (generally in the range of about 80 to about with gaseous chlorine monoxide (generally in the range of about 0.1 to about 1.0%

on the weight of dry fabric) diluted with an inert gas,

e.g. air, nitrogen, oxygen, etc. to a partial pressure of from about 1 to about 253 Torr.

The fabric, in contact with the gaseous chlorine monoxide, is generally at a moisture content from about 80 to about 20%, for a contact time of from a fraction of a second up to about 300 seconds, at ambient temperature, and at a terminal pH selected to be a narrow range within the limits of about I to about 13.

By another aspect of this invention, the fabric is we treated with an alkaline material (i.e. NaOH or Na CO in such a manner that the terminal pI-I, after addition of the chlorine monoxide, will be a selected one within the limits of about 1 to about 13. The terminal pH, after the treatment with chlorine monoxide, has a significant effect on the brightness of the fabric obtained, but not a significant effect on the fluidity. Thus, it was found that the highest brightness values were obtained in the alkaline range for the particular blend of fabric used in these experiments.

It has surprisingly been found that, in bleaching the raw, natural fibers, such as, for example, cotton, and synthetic fibers, such as, for example, polyesters, in open-width form, at a moisture content of about 80 to about 20%, using gaseous chlorine monoxide, it is possible to achieve an Elrepho brightness of 92 in a very short period of time, e.g. of the order of a fraction of one second up to about 300 seconds. In the past, such a brightness was not possible to achieve even after a substantially larger period of bleaching time (2 hours), using, e.g. a conventional hydrogen peroxide solution for bleaching.

This result is more surprising when one considers the fact that chlorine monoxide is now known for bleaching a cellulose pulp but only when such pulp is athigh consistency, in fluffed or shredded form, with gaseous chlorine monoxide (see U.S. Pat. No. 3,619,349 issued Nov. 9, 1971 and Canadian Pat. No. 899,005 issued May 2, 1972, each to Norman Liebergott and Henry Irving Bolker, assigned to the Pulp and Paper Research Institute of Canada). It was found in the above-noted patents to be essential for the successful bleaching of the pulp for the pulp to be in fluffed or shredded form. As will be seen later in comparative tests, pulp in unbleached sheet or paper form could not successfully be bleached using gaseous chlorine monoxide.

DESCRIPTION OF PREFERRED EMBODIMENTS The following are examples of aspects and embodiments of this invention. Test methods used for brightness and fluidity are as follows:

Brightness or Whiteness: measure on an Elrepho reflectometer using a blue filter at 457 nm.

Fluidity: ASTM method D539-53.

EXAMPLE 1 A starch-sized, cream-coloured cotton/polyester fabric (/50), characterized by an Elrepho brightness of 56.2 and a fluidity of 2.5, was soaked in tap water to bring the moisture content of the fabric to EXAMPLE la A portion of the fabric was passed into a reaction vessel. Chlorine monoxide, diluted with air to a partial pressure of 200 Torr, was passed into the reaction vessel until 02% chlorine monoxide, based on the oven dry weight of fiber, was added to the fabric in twenty seconds. The terminal pH of the fabric was 4.7 after the twenty second treatment. The bleached fabric was removed, washed with water, air dried, and the brightness and fluidity measured.

The brightness was 73 on the Elrepho meter, and the fabrid had a fluidity of 3.9.

EXAMPLE 1b Another portion of the prepared, open-width fabric was sprayed with a solution containing 1.5% Na CO on the weight of dry fabric. The moisture content of the web was 75%. The web was placed into a reaction flask. Chlorine monoxide, diluted with air to a partial pressure of 200 Torr, was passed into the reaction flask until 0.2% chlorine monoxide, based on the oven dry weight of fiber, was added to the fabric in twenty seconds. The terminal pH of the fabric was 6.6 after the twenty second treatment. The bleached fabric was washed with water, air dried, and the brightness and fluidity measured.

The brightness was 78, and the fluidity was 4.1.

EXAMPLE 1c Another portion of the unbleached, open-width fabric was sprayed with a solution containing 5% Na CO on the weight of dry fiber, and the moisture content of the fiber was 75%. The fabric was placed in a reaction chamber. Chlorine monoxide, diluted with air to a partial pressure of 200 Torr, was passed into the reaction chamber until 0.2% chlorine monoxide, based on the oven dry weight of fiber, was added to the fiber in twenty seconds time. The terminal pH of the fabric, after the twenty second treatment, was 8.2. The bleached fabric was washed with water, air dried, and the brightness and fluidity measured.

The brightness was 81.0 and the fluidity was 4.0.

EXAMPLE 1d Another portion of the unbleached, open-width fabric was sprayed with a solution containing 7% 1\Ia CO on the weight of dry fiber, and the moisture content of the fiber was 75%. The fabric was placed in a reaction chamber. Chlorine monoxide, diluted with air to a partial pressure of 200 Torr, was passed into the reaction chamber until 0.2% chlorine monoxide, based on the oven dry weight of fiber, was added to the fiber in twenty seconds time. The terminal pH of the fabric, after the twenty second treatment, was 9.8. The bleached fabric was washed with water, air dried, and the brightness and fluidity measured.

The brightness was 87 and the fluidity was 3.9.

EXAMPLE 2 A starch-sized, cotton/polyester fabric was de-sized by soaking at one percent consistency in a solution con taining 10% NaOH on the weight of dry fabric, at 70F. The fabric was then pressed to a moisture content of 30%.

EXAMPLE 2a A portion of the de-sized fabric was passed into a reaction vessel. Chlorine monoxide, diluted with air to a partial pressure of 5 Torr, was passed into the reaction vessel until 0.2% chlorine monoxide, based on the oven dry weight of fiber, was added to the fabric in one minute. The terminal pH of the fabric was 6.2 after the one minute treatment. The bleached fabric was removed, washed with water, air dried, and the brightness and fluidity measured.

The brightness was 83.9 and the fluidity was 4.1.

EXAMPLE 2b Another portion of the de-sized fabric was sprayed with a solution containing 1% NaOH on the dry weight of fabric. The moisture content of the fabric was 25%. The fabric was placed in a reaction flask. Chlorine monoxide, diluted with air in a partial pressure of 5 Torr, was passed into the reaction flask until 0.2% chlorine monoxide, based on the oven dry weight of fiber, was added to the fabric in one minute. The terminal pH of the fabric was 9.8 after the one minute treatment. The bleached fabric was washed with water, air dried, and the brightness and fluidity measured.

The brightness was 92, and the fluidity was 4.3.

EXAMPLE 3 General experiments were conducted using chlorine monoxide dissolved in carbon tetrachloride to bleach in open-width form a raw, natural fiber in combination with a synthetic fiber.

Starch-sized, cream-coloured cotton/polyester fabric (50/50) characterized by an Elrepho brightness of 56.2 was used in the following test:

Portions of the fabric were passed into a solution of carbon tetrachloride containing 8.9 g/l of chlorine monoxide and left to reside for retention times of 1 minute, 5 minutes, 15 minutes and 30 minutes. The treated fabrics were removed after each respective time period from the chlorine monoxide carbon tetrachloride solution, washed copiously with water, air dried, and the brightness measured. The brightnesses obtained are listed below.

min.

It is noted that, in the same bleaching time, the brightnesses obtained in these experiments were lower than the brightnesses obtained with gaseous chlorine monoxide. However, it is noted that, for example, brightnesses of the same general range as in Examples 1 and 2 were obtained, even though the treating time would have to be increased from 20 seconds (in Example l) to 30 minutes. However, the prior art has been generally unable to bleach to such brightness unless the bleaching time was 2 hours or more.

Although the solvent used in Example 3 was carbon tetrachloride, it is known that chlorine monoxide is readily soluble in various organic liquids. Other suitable solvents are those which are inert to the textile being bleached, and include trichloroethylene, tetrachloroethylene, and the fluorocarbon solvents known by the Trade Mark of Freon.

COMPARATIVE TEST A Test Ai Using hydrogen peroxide, a portion of the de-sized cotton/polyester fabric of Example 1 was treated with a peroxide solution under the following conditions:

H 1 0.6% H 0 on the dry weight of fabric Na SiO 3% NaOH 2% pH 10.5 Temperature I 180F. Time 2 hours After using a 1% solution of H 50 as an antichlor, the fabric was washed and air dried, and the brightness and fluidity measured.

The brightness was 82.0 and the fluidity was 3.1.

Test Aii Using acidified sodium chlorite, a portion of the desized cotton/polyester fabric of Example 1 was treated with a sodium chlorite solution under the following conditions:

as available chlorine on the Na C1O, 1.2%

weight of dry fiber sodium acetate: 0.5% on the weight of dry fiber glacial acetic acid 0.05% pH 4 Time 1 hour Temperature 100F.

After souring with a solution of H SO the fabric was washed and air dried and the brightness and fluidity measured.

The brightness was 67.1 and the fluidity was 3.9.

The results of the above examples and comparative tests are summarized in the table below. As noted above, the fabric was a cotton/polyester fabric, having an initial Elrepho brightness of 56.2 and an initial fluidity of 2.5.

increase due to Treatment Brightness Example 5 (points) Fluidity 16.8 1 4 1(b) 21.8 1.6 1(c) 24.8 1.5 1(d) 30.8 1.4 2(a) "27.7 1.6 2(b) 35.8 1.8 3 23.6 (unknown) A(i) 25.8 0.6 A(ii) 10.9 1.4

As shown in the table, bleaching with carbon monoxide is as effective as bleaching with hydrogen peroxide, but is more effective than bleaching with acidified sodium chlorite, and the bleaching takes place in the order of seconds, i.e. one minute or less (when gaseous chlorine monoxide is used) and in the order of minutes, i.e. 30 minutes (when chlorine monoxide in a liquid solvent is used), instead of two hours.

COMPARATIVE TEST B The terminal pH was 3.0. The brightness was then measured.

The brightness was 88.1.

Test Bii A partially delignified sulphite pulp, having a Kappa No. of 1.0, and an Elrepho brightness of 57.5, was formed into a handsheet having a moisture content of and a basic weight of 40 lbs. per 3,000 square feet. It was then treated with chlorine monoxide at a partial pressure of 210 Torr, for 1 minute, until the amount added was 0.6% based on oven-dried pulp. The terminal pH was 3.0. The brightness was then measured.

The brightness was only 72.3.

This Experiment shows that the level of brightness obtained on shredded or fluffed pulp is far superior than that obtained on handsheets at the same moisture content by the same process. Thus, the brightness increase on the fluffed pulp is 20.4, while the brightness increase on the handsheet is only 14.6. Moreover, pulp bleached to an Elrepho brightness of 72.3 is generally considered to be inadequately bleached. Thus, it is believed known that fibers in sheet form could not be successfully bleached with chlorine monoxide. Accordingly, it is believednon-obvious that textile fibers, either in rope form or fabric form, could be successfully bleached with chlorine monoxide.

CONCLUSIONS The preceding examples can be repeated with similar success by substituting the generically and specifically described reactants and operating conditions of this invention for those used in the preceding examples.

From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. Consequently, such changes and modifications are properly, equitably, and intended to be, within the full range of equivalent of the following claims. 1

We claim:

1. In a process for the bleaching of textile materials, either in open-width or rope form, and at a suitable moisture content, the improvement which comprises contacting said textile materials with chlorine monoxide in admixture with an inert gaseous or liquid carrier.

2. The process of claim 1 wherein the chlorine monoxide is in admixture with an inert gas.

3. The process of claim 1 wherein the chlorine monoxide is in solution in an inert liquid solvent.

4. A process for the bleaching of fabrics either in open-width or rope form, said fabrics including a raw natural fiber, either alone or in combination with a synthetic fiber, which comprises contacting said fabrics at a suitable moisture content, with chlorine monoxide in an amount of about 0.1 to about 1.0% on the weight of the dry fabric.

5. The process of claim 4 wherein the chlorine monoxide is diluted with a gas to a partial pressure of from about 1 to about 253 Torr.

6. The process of claim 5 wherein said diluent gas is air.

7. The process of claim 4 wherein the chlorine monoxide is in a carbon tetrachloride solution.

8. The process of claim 5 wherein said moisture content is in the range of about to about 20%.

9. The process of claim 7 wherein said moisture content is in the range of about 80 to about 20%.

10. The process of claim wherein the process is carried out to a terminal pH selected to fall within the range of about 1 to about l3.

11. The process of claim 7 wherein the process is carried out to a terminal pl-l selected to fall within the range of about 1 to about 13.

12. The process of claim 5 wherein said contacting time is from less than about 1 second up to about 300 seconds.

13. The process of claim 1 including an alkaline pretreatment.

14. The process of claim 1 including an alkaline pretreatment with NaOH or Na CO- 15. The process of claim 1 including a de-size washing step and a caustic soda scour step prior to the chlorine monoxide contacting step, and a washing step and a drying step subsequent to the chlorine monoxide contacting step.

16. The process of claim 4 wherein the chlorine monoxide is diluted with air to a partial pressure of from about 1 to about 253 Torr; wherein the moisture content is about 80 to about wherein the contacting time is from less than about 1 second to about 300 seconds; and wherein the terminal pH is selected to fall within the range of about 1 to about 13.

17. The process of claim 16 wherein the fabric is a blend of cotton and polyester, having a moisture content of about 70%; wherein the chlorine monoxide is diluted with air to a partial pressure of about 200 Torr; wherein the amount of chlorine monoxide is about 0.2%; wherein the contacting time is about 20 seconds; and wherein the terminal pH is about 4.7.

18. The process of claim 16 wherein the fabric is a blend of cotton and polyester; wherein the fabric is treated with a solution containing about 1.5% Na CO wherein the moisture content is about 75%; wherein the chlorine monoxide is diluted with air to a partial pressure of about 200 Torr; wherein the amount of chlorine monoxide is about 0.2%; wherein the contacting time is about 20 seconds; and wherein the terminal pH is about 6.6.

19. The process of claim 16 wherein the fabric is a blend of cotton and polyester; wherein the fabric is treated with a solution containing about 5% Na CO wherein the moisture content is about 75%; wherein the chlorine monoxide is diluted with air to a partial pressure of about 200 Torr; wherein the amount of chlorine monoxide is about 0.2%; wherein the contacting time is about 20 seconds; and wherein the terminal pH is about 8.2.

20. The process of claim 16 wherein the fabric is a blend of cotton and polyester; wherein the fabric is treated with a solution containing about 7% Na CO wherein the moisture content is about 75%; wherein the chlorine monoxide is diluted with air to a partial pressure of about 200 Torr; wherein the amount of chlorine monoxide is about 0.2%; wherein the contacting time is about 20 seconds; and wherein the terminal pH is about 9.8.

21. The process of claim 16 wherein the fabric is a blend of cotton and polyester; wherein the fabric is desized by soaking at one percent consistency in a solution containing about 10% NaOH at about F; wherein the fabric has a moisture content of about 30%; wherein the chlorine monoxide is diluted with air to a partial pressure of about 5 Torr; wherein the amount of chlorine monoxide is about 0.2%; wherein the contacting time is about 60 seconds; and wherein the terminal pH is about 6.2.

22. The process of claim 16 wherein the fabric is a blend of cotton and polyester; wherein the fabric is desized by soaking at one percent consistency in a solution containing about 10% NaOH at about 70F; wherein the fabric is further treated with a solution containing about 1% NaOH; wherein the moisture content of the fabric is about 25%; wherein the chlorine monoxide is diluted with air to a partial pressure of about 5 Torr; wherein the amount of chlorine monoxide is about 0.2%; wherein the contacting time is about 60 seconds; and wherein the terminal pH is about 9.8.

23. The process of claim 7 wherein the fabric is a blend of cotton and polyester, having a moisture content of about 70%; wherein the chlorine monoxide is dissolved in carbon tetrachloride to a concentration of about 8.9 g/l; and wherein the contacting time is about 1 minute to about 30 minutes. 

1. IN A PROCESS FOR THE BLEACHING OF TEXTILE MATERIALS, EITHER IN OPEN-WIDTH OR ROPE FORM, AND AT A SUITABLE MOISTURE CONTENT, THE IMPROVEMENT WHICH COMPRISES CONTACTING SAID TEXTILE MATERIALS WITH CHLORINE MONOXIDE IN ADMIXTURE WITH AN INERT GASEOUS OR LIQUID CARRIER.
 2. The process of claim 1 wherein the chlorine monoxide is in admixture with an inert gas.
 3. The process of claim 1 wherein the chlorine monoxide is in solution in an inert liquid solvent.
 4. A process for the bleaching of fabrics either in open-width or rope form, said fabrics including a raw natural fiber, either alone or in combination with a synthetic fiber, which comprises contacting said fabrics at a suitable moisture content, with chlorine monoxide in an amount of about 0.1 to about 1.0% on the weight of the dry fabric.
 5. The process of claim 4 wherein the chlorine monoxide is diluted with a gas to a partial pressure of from about 1 to about 253 Torr.
 6. The process of claim 5 wherein said diluent gas is air.
 7. The process of claim 4 wherein the chlorine monoxide is in a carbon tetrachloride solution.
 8. The process of claim 5 wherein said moisture content is in the range of about 80 to about 20%.
 9. The process of claim 7 wherein said moisture content is in the range of about 80 to about 20%.
 10. The process of claim 5 wherein the process is carried out to a terminal pH selected to fall within the range of about 1 to about
 13. 11. The process of claim 7 wherein the process is carried out to a terminal pH selected to fall within the range of about 1 to about
 13. 12. The process of claim 5 wherein said contacting time is from less than about 1 second up to about 300 seconds.
 13. The process of claim 1 including an alkaline pretreatment.
 14. The process of claim 1 including an alkaline pretreatment with NaOH or Na2CO3.
 15. The process of claim 1 including a de-size washing step and a caustic soda scour step prior to the chlorine monoxide contacting step, and a washing step and a drying step subsequent to the chlorine monoxide contacting step.
 16. The process of claim 4 wherein the chlorine monoxide is diluted with air to a partial pressure of from about 1 to about 253 Torr; wherein the moisture content is about 80 to about 20%; wherein the contacting time is from less than about 1 second to about 300 seconds; and wherein the terminal pH is selected to fall within the range of about 1 to about
 13. 17. The process of claim 16 wherein the fabric is a blend of cotton and polyester, having a moisture content of about 70%; wherein the chlorine monoxide is diluted with air to a partial pressure of aboUt 200 Torr; wherein the amount of chlorine monoxide is about 0.2%; wherein the contacting time is about 20 seconds; and wherein the terminal pH is about 4.7.
 18. The process of claim 16 wherein the fabric is a blend of cotton and polyester; wherein the fabric is treated with a solution containing about 1.5% Na2CO3; wherein the moisture content is about 75%; wherein the chlorine monoxide is diluted with air to a partial pressure of about 200 Torr; wherein the amount of chlorine monoxide is about 0.2%; wherein the contacting time is about 20 seconds; and wherein the terminal pH is about 6.6.
 19. The process of claim 16 wherein the fabric is a blend of cotton and polyester; wherein the fabric is treated with a solution containing about 5% Na2CO3; wherein the moisture content is about 75%; wherein the chlorine monoxide is diluted with air to a partial pressure of about 200 Torr; wherein the amount of chlorine monoxide is about 0.2%; wherein the contacting time is about 20 seconds; and wherein the terminal pH is about 8.2.
 20. The process of claim 16 wherein the fabric is a blend of cotton and polyester; wherein the fabric is treated with a solution containing about 7% Na2CO3: wherein the moisture content is about 75%; wherein the chlorine monoxide is diluted with air to a partial pressure of about 200 Torr; wherein the amount of chlorine monoxide is about 0.2%; wherein the contacting time is about 20 seconds; and wherein the terminal pH is about 9.8.
 21. The process of claim 16 wherein the fabric is a blend of cotton and polyester; wherein the fabric is de-sized by soaking at one percent consistency in a solution containing about 10% NaOH at about 70*F.; wherein the fabric has a moisture content of about 30%; wherein the chlorine monoxide is diluted with air to a partial pressure of about 5 Torr; wherein the amount of chlorine monoxide is about 0.2%; wherein the contacting time is about 60 seconds; and wherein the terminal pH is about 6.2.
 22. The process of claim 16 wherein the fabric is a blend of cotton and polyester; wherein the fabric is de-sized by soaking at one percent consistency in a solution containing about 10% NaOH at about 70*F.; wherein the fabric is further treated with a solution containing about 1% NaOH; wherein the moisture content of the fabric is about 25%; wherein the chlorine monoxide is diluted with air to a partial pressure of about 5 Torr; wherein the amount of chlorine monoxide is about 0.2%; wherein the contacting time is about 60 seconds; and wherein the terminal pH is about 9.8.
 23. The process of claim 7 wherein the fabric is a blend of cotton and polyester, having a moisture content of about 70%; wherein the chlorine monoxide is dissolved in carbon tetrachloride to a concentration of about 8.9 g/l; and wherein the contacting time is about 1 minute to about 30 minutes. 